Pre-Incubatee/Summer Research Intern - Medical Electronics
May 2017 - July 2017 Medical Electronics Biomedical Implants Thermal Energy Harvesting
It started with the selection as the youngest person for the incubation support by the Incubation Center for medical electronics at the Indian Institute of Technology (IIT), Patna, India. I got the support & guidance of Prof. Dr. Kailash Chandra Rayto kick start the project on developing micro thermal energy harvesting systems for biomedical implants like a pacemaker. I worked for nearly a whole year, which comprises working the whole summer in the labs at IIT Patna. So, down below I would like to give a concise description of what this is all about & what we achieved as we move ahead in the project.
Introduction:
As technology makes rapid strides in all spheres of everyday life, there arises the enduring demand for health-care and monitoring devices that are not only accurate but also efficient. Many of the bio-sensors and bio-devices today are implantable, which means that they are embedded inside the body of the subject. Understandably, then, arises the question of powering such devices.
The answer to which is: Wireless Charging.
Millions of people around the world benefit from having artificial pacemakers implanted into their chests, to help restore a normal heartbeat. Yet pacemakers are not without problems. The bulk of the device—which contains its battery and electronic control systems—usually sits just under the wearer's skin. From this box thin, flexible leads are threaded through a vein and into the appropriate part of the heart. These leads detect the heart's electrical activity (which controls when it contracts and is regulated by a cluster of specialized muscle cells that act as a natural pacemaker), transmit that information to the artificial pacemaker's electronics for analysis and, if the natural activity is deemed irregular, deliver an electrical charge from the artificial pacemaker's batteries that causes the cardiac muscle to contract, pacing the pumping of the heart. Currently, many of these devices run on big, long-lasting batteries that still eventually die, generally requiring another round of surgery. Thus to eliminate the bulky batteries and clumsy recharging systems that prevent medical devices from being more widely used, we devised a pacemaker with wireless charging capabilities in order to reduce surgical risk to patients and associated healthcare costs. Earlier, the pacemaker needed to be replaced surgically when the battery run out. With this project, the painstaking and risky process is no longer required!
So, we started working under the guidance of Prof. Dr. Kailash Chandra ray at the Department of Electrical Engineering, Indian Institute of Technology (IIT), Patna, India on bringing this concept into reality. Initially, we started our research on using inductor on-chip for energy transfer but as we move ahead in the project we work on developing a complete thermal energy harvesting power supply for implantable pacemakers which includes an internal startup and does not need any external reference voltage. The startup circuit includes a prestart up charge pump (CP) and a startup boost converter. The prestart up CP consists of an ultralow-voltage oscillator followed by a high-efficiency modified Dickson. Forward body biasing is used to effectively reduce the MOS threshold voltages as well as the supply voltage in oscillator and CP. The steady-state circuit includes a high-efficiency boost converter that utilizes a modified maximum power point tracking scheme. The system is designed so that no failure occurs under overload conditions. However as we made further progress, we worked on bringing a standalone thermoelectric platform that can integrate our previous ( i.e TEG based Power Supply with Internal Startup Circuit for Pacemakers) power management IC with customized TEH (Thermoelectric Heat Pump) into a single microsystem with a regulated output power which is roughly twice the power we need to operate a pacemaker.